My wife and I adopted a rescue dog a couple of months ago, so I’ve been taking two or three extra walks a day, which have turned out to be perfect for listening to podcasts of This American Life. I love the radio program, but I didn’t always have time for it because I tend to prefer reading during my commute, and there are books, movies, and video games competing for my free time at home. Still, the Android app for the show was my first paid download when I got a Droid phone, and now I’m actually getting a lot more use out of it.

Anyway, I was astonished the other day when I heard the January 11, 2013 episode, “Doppelgängers.” As you might be aware, a doppelgänger is an identical twin, what Wikipedia defines as “a paranormal double of a living person, typically representing evil or misfortune.” The German word literally translates as “double goer.” Doppelgängers are staples of parallel universe and time travel stories, but it seems they appear in pretty much every genre, whether in a purely symbolic representation in literary fiction or something more sinister in horror. As fascinating as it might be to encounter someone who looks just like you, who might have led a life different from your own, the possibility of being replaced by your duplicate–cloned or dimensional or whatever–is terrifying.

The episode of This American Life is much more grounded in reality, but some of the implications raised by its stories are no less horrific. The hour-long program is often startling, humorous, sobering and profound, presenting two pieces that celebrate the redemptive power of pork bung and compare and contrast life in Philadelphia with the war in Afghanistan. Check it out:

I think I’m gonna have to say the original Invasion of the Body Snatchers. Or Dave for something not scary.

There are so many different things you can do with the concept. The horror aspects of replacement or insanity. Adventure like The Prisoner of Zenda or The Prince and the Pauper. Humor like The Parent Trap/Lottie and Lisa.

I suppose the people who really have to confront this are the most interesting, those very special cases so beloved of psychological researchers: twins separated at birth and raised by different families. Learning that about yourself has got to be really disorienting at first.

And unsurprisingly I am fascinated by twins studies. One of the books I’m working on is about identical twins, but as you pointed out, variations on that story have been told many times so I’m trying to figure out what to do with it.